The investigators propose to study the safety of autologous mesenchymal stromal cell transfer using a biomatrix (the Gore Fistula Plug) in a Phase I study using a single dose of 20 million cells. 15 adult patients, ages 18 years and older with cryptoglandular fistulas will be enrolled. Subjects will undergo standard adjuvant therapy including drainage of infection and placement of a draining seton. Six weeks post placement of the draining seton, the seton will be replaced with the MSC loaded Gore Fistula Plug; fistula plug as per current clinical practice. The subjects will be subsequently followed for fistula response and closure for 24 months. This is an autologous product derived from the patient and used only for the same patient.